87

ORIGINAL ARTICLEMalaysian Journal of Medical Sciences, Vol. 10, No. 2, July 2003 (87-90)

ROTAVIRUS - A RETROSPECTIVE STUDY OF INCIDENCEAT THE HOSPITAL UNIVERSITI SAINS MALAYSIA (HUSM)

C.M. Mat Ludin, J. Md.Radzi , and A.Maimunah

Department of Microbiology and ParasitologySchool of Medical Sciences, Universiti Sains Malaysia, Health Campus

16150 Kubang Kerian, Kelantan, Malaysia

The present study, analyzes data from 1991 to 2000 for rotavirus infection amongchildren with diarrhoea and acute gastroenteritis admitted to the HospitalUniversiti Sains Malaysia (HUSM). The Latex Slide Agglutination Test was usedfor the detection of rotavirus antigens. Out of 1097 stool samples tested, 207 samplesor 18.8 % were found to be positive for rotavirus. The infection occurred mostfrequently in infants and young children from 6 months to 2 years of age. Theinfection was recorded highest in the year of 2000 - 48 cases (34.1%) and the lowestin 1999 - 5 cases (6.6%). Stool examination and cultures from the rotavirus positivesamples revealed no parasites and enteropathogenic bacteria. These observationssuggested that rotavirus could still remain as an important agent causing diarrhoeaand gastroenteritis in young children admitted to HUSM.

Key words : Rotavirus, gastroenteritis, latex agglutination

Introduction

Rotavirus infection is a major cause of severediarrhoea in infants and young children all over theworld. Although, the infection is no longer a majorcause of childhood death in Malaysia, it remains amajor cause of morbidity in infants and youngchildren. It is most severe in children between theages of 6 months and 2 years. It is generally acceptedthat neonatal rotavirus infections are withoutsymptoms. This is probably due to the presence ofmaternal antibody protection (5). Two viral surfaceproteins, P and G, are thought to be immunologicallyimportant since they induce type-specificneutralising antibodies. Many different variants havebeen described, but in Europe, Asia and the USAmost strains belong to the genotype p (4) G2 orcombinations of P (8) with G1, 3, or 4.1 (5). It isnotable that many candidate rotavirus vaccines arebased on the G1-4 strains.

Rotavirus infection may be highly contagious.Children and adults can become infected on cominginto direct contact with the virus that are in the feces

of an infected child and then passing on those virusesto the mouth (fecal-oral transmission). Resistanceto physical inactivation (along with the large numberof viral particles shed in feces) may contribute tothe efficient transmission of the human rotaviruses.However, the source of infection in infants andneonate - those not normally in contact with otherinfants and young children with gastroenteritis, isnot well documented. It is most likely that infectionis acquired from an older sibling or parents with subclinical infection (2). The aim of this study is toestimate the prevalence of rotavirus gastroenteritisin HUSM and other pathogens associated with thisinfection.

Methodology

This is a retrospective analysis of all stoolsamples of children admitted to the HUSM over thelast 10 years suspected of having rotavirus infection.In this study, the rotavirus was detected byexamining the stool specimen using commercial kit“Serobact Rotavirus Latex Slide Agglutination Test”

Submitted-22.12.2002, Revised-18.6.2003, Accepted-18.6.2003

88

Medvet Science PTY LTD, Australia for thedetection of rotavirus antigens. When a stool extractwas mixed with the test latex reagent any rotavirusantigens present will react with the sensitizingantibodies, resulting in visible agglutination of thelatex particles. In each test, positive and negativecontrol samples were also included. The stoolsamples were also examined and cultured in anappropriate media such as MacConkey, DCA andCCDA for the present of enteropathogenic bacteriaand parasites.

Results

The total number of specimens analysed andthe results of rotavirus test obtained for each yearwithin a 10 years of period are shown in table 1.Out of the 1097 stool samples studied, 207 or 18.8%were found to be positive for rotavirus, 7.93% forenteric pathogen and negative for parasites as shownin table 2. The enteropathogenic bacteria isolatedwere Salmonella sp. (2.37%), Shigella flexneri(2.28%), Escherichia coli (3.92%), Campylobacter

jejuni (0.18%) and Salmonella typhi (0.18%) asshown in pie chart in figure 1. Stool examinationand cultures from the rotavirus positive revealed noparasites and enteropathogenic bacteria.

All the patients with rotavirus positive werechildren aged under 2. The disease was prevalent inboth sexes and in all races. The rotavirus infectionamong children with diarrhoea and gastroenteritiswas recorded highest in the year 2000, (48 cases -34.1%) and the lowest infection was recorded in1999, (5 cases - 6.6%) as shown in table 1.

Discussion

Rotavirus organism seems to be a virus ofsignificance in infant and young children withdiarrhoea and gastroenteritis in HUSM. Althoughonly 18.8% of the children’s with diarrhoea andgastroenteritis in our study shed rotavirus in theirfeces, nevertheless these findings support previousobservations that the disease is prevalent in infantand young children (2). Other etiologic agentsaccounting for a relatively small number of episodes

C.M. Mat Ludin, J. Md.Radzi et. al

Table 1. The total number of specimens analyzed and the results of rotavirus testobtained from 1991-2000.

Table 2. Prevalence of rotavirus infection and other pathogens isolated amonginfants and children with diarrhoea and gastroenteritis

Year

1991199219931994199519961997199819992000

Total

Total Number ofSpecimens

1338576

118121114105136

75141

1097

Rotavirus Positive

1768

31

29281223

548

207

Percentage

12.77.0

10.526.223.924.511.416.9

6.634.1

18.8

Total sampleExamined

Ratovirus Parasites Enteric pathogen

1097 % 20118.8

Nil -

877.9

89

of gastroenteritis was the enteropathogenic bacteriasuch as Escherichia coli, Salmonella spp. Shigellaspp. and parasites of Cryptosporidium spp. Recently,there was a report on outbreak of rotaviruses thatcaused neonatal diarrhoea in a paediatric ward inthe Netherlands. The genotype P (6) G9 rotaviruswas the cause of the outbreak (5). This high attackrate may, in part, be due to the lack of protectiveantibodies in a high proportion of neonates, since P(6) G9 rotaviruses have not been previously foundin the Netherlands and therefore mothers may nothave been exposed to this genotype. In this study,the genotyping of the rotavirus grouping was notperformed. Stool examination and cultures from therotavirus positive samples revealed no parasites orenteropathogenic bacteria, suggesting that rotaviruscould remain as an important agent in the causationof severe diarrhoea in young children admitted toHUSM. The infection was reported to be moresevere in children between 6 months and 2 years ofage, whereas neonatal rotavirus infections weregenerally accepted as symptom less, suggesting thatit is probably due to maternal antibody protection(5-6).

Rotavirus infections display a consistentpattern throughout the year but with slightly higherincident in year 2000, where 48 cases or 34.1% hadbeen reported. While a lower infections rate wasrecorded in 1999 where 5 cases or 6.6% of rotaviruspositive were reported. However, no rotavirusoutbreaks were reported during the 10 years periodof studies. In temperate countries, it shows seasonalpattern of infection. Classically, an outbreak occursduring the winter months, especially at the day-carecentre and children hospitals (4).

Rotaviruses appear to be transmitted by thefecal-oral route. Children and adults can be infectedvia direct contact with the viruses that are in thefeces of an infected child and then passing on thoseviruses to the mouth. Resistance to physicalinactivation (along with the large number of viralparticles shed in feces) may contribute to the efficienttransmission of the human rotavirus. The source ofinfection for the young infant who is normally notin contact with other infants and young children withgastroenteritis is not well documented. Infection ismost likely acquired from an older sibling or parentwith sub clinical infection or from environmentalcontamination such as nosocomial infection inhospital and nurseries.

There has been speculation on the role ofanimals as a source of rotavirus infection to human(3). Because certain animal rotavirus share aneutralizing antigen with human rotavirus and somenatural occurring animal rotavirus strains may infecthumans. Nonetheless, this types of interspeciesinfection appear to be a rare event.

The ability of rotavirus to survive on varioussurfaces under different conditions may alsocontribute to the rapid spread of these agents.However, relatively high humidity (~ 80%) resultsin a rapid loss in human rotavirus infectivity.Therefore, the incidence of rotavirus infection inHUSM (18.8%) is relatively low compared to thoseseen in temperate countries such as in the UK (52%)and Finland (49%) (Cook et, al.,1990). Effectivedisinfections of contaminated material and carefulhand washing constitute important measures tocontain rotavirus infection, especially in hospital andother institutional settings.

Figure 1. The percentage of enteropathogenic bacteria found in stoolexamination for rotavirus.

ROTAVIRUS - A RETROSPECTIVE STUDY OF INCIDENCE AT THE HOSPITAL UNIVERSITI SAINS MALAYSIA (HUSM)

73.20%

2.92%

2.37%

2.28%

0.18%

0.18%

18.87%

E.coliSamonella sp.Shigella �exneriCampylobacter jejuniS. typhiPositive rotavirusNegative rotavirus

90

The clinical manifestations of rotavirus illnessare not sufficiently distinctive to permit diagnosison this basis alone. Therefore, diagnosis requiresdetection of virus or viral antigen and / ordemonstration of a serologic response. Theepidemiologic pattern may provide additionalinformation to aid in diagnosis, but laboratoryconfirmation is required. Various methods areavailable for the detection of rotavirus in stoolspecimens. The method of choice is the Latex SlideAgglutination Test since it is highly sensitive,specific, does not require specialized equipment andhas a built-in control for non-specific reaction.

Conclusion

Although the incidence of rotavirus infectionin HUSM is relatively low as compared to that oftemperate countries, the viruses remain as animportant agent in the causation of gastroenteritisand diarrhoea. Illness is most severe in childrenbetween 6 months and 2 years of age, whereasneonatal rotavirus infections are generallysymptomless because of maternal antibodyprotection. It show seasonal pattern of infection inthe temperate countries but not in a tropical setting.The Latex Slide Agglutination Test (commercial kit)is the method of choice for the detection of rotavirusantigen in fecal specimens because it is rapid, highlysensitive, specific and more convenient comparedto ELISA and electron microscopy. Theenteropathogenic bacteria is not frequently isolatedin gastroenteritis associated with rotavirus infection.There are also cases showing concomitant infectionby enteropathogenic bacteria in rotavirusgasteroenteritis, but these rarely occurred.

Correspondence :

En. Mat Ludin Che Mat Bsc. (Hons), BradfordUniversiti U.K.Department of Microbiology and ParasitologySchool of Medical Sciences,Universiti Sains Malaysia, Health Campus16150 Kubang Kerian, Kelantan, Malaysia

References

1. Cook SM., Glass TI., LeBaron CW., Ho MS., 1990.Global seasonality of rotavirus infections, Bull WHO.68,171 - 177.

2. Gurwith M., Wenmen W., Hinde D., Feltham S.,Greeberg H., 1981. A prospective study of rotavirusinfection in infants and young children. J. Infect.Dis.144, 218 - 224.

3. Garbarg-Chenon A., and Nicolas JC., Bouvier M. 1986.Epidemiology and genomic study of rotavirus strainsinfecting young children and calves in the same ruralenvironment. EUR. J. Epidemiol. 2,108 - 111.

4. Inouye S., Yamashita K., Yamadera S., Yoshikawa M.,Kato N., Okabe N.2000. Surveillance of viralgastroenteritis in Japan: pediatric cases and oubreakincidents. J. Infect. Dis. 181, Suppl 2, 270 - 274.

5. Marc-Alain Widdowson., Gerard JJ van Doornum.,Wim H M van der Poel., Annette S de Boer. 2000.Lancet. 356, 1161 - 1163.

6. Oishi I., Kimura T., Murakami T., 1991. Serialobservations of chromic rotavirus infection in animmunodeficient child. Microbial immunol. 35 : 953- 961.

C.M. Mat Ludin, J. Md.Radzi et. al